Catalytic slurry process for black oil conversion with hydrogen and ammonia

ABSTRACT

A catalytic slurry process for effecting the conversion of a hydrocarbonaceous charge stock containing asphaltenes and metallic contaminants. The slurry constitutes charge stock, hydrogen, from about 1.0 to about 25.0 percent by weight of finely divided catalyst particles and, in a preferred embodiment, a portion of the previously produced product effluent. Preferred catalysts are the unsupported sulfides of the metals from Groups V-B, VI-B and VIII. Prior to an initial separation, hydrogen sulfide is commingled with the product effluent in order to convert the metals contained therein to the sulfides thereof.

ited States Patent 72] Inventors Laurence 0. Stine 3,074,879 1/1963Weekman 208/ 1 76 Western Springs; 3,161,585 12/1964 Gleim et al.208/264 Frank Stolfa, Park Ridge, both of I11. 3,231,488 [/1966 Gatsiset al. 208/264 [21] Appl. No. 4,806 3,558,474 l/l97l Gleim et al.208/108 [22] F'led 1970 Primary ExaminerDelbert E. Gantz [45] PatentedNov. 23, 1971 ni rsal on Prod C Assistant ExammerG. E. SchmItkons [73 1Asslgnee U W ompany Attorneys-James R. Hoatson, Jr. and Robert W.Erickson Des Plaines, III.

1 OGEN AND AMMONIA y g g CONYERSION WITH asphaltenes and metalliccontaminants. The slurry constitutes 7 Chums 1 Drawing charge stock,hydrogen, from about 1.0 to about 25 .0 percent [52] US. Cl 208/108, byweight of finely divided catalyst particles and, in a 2081102, 208/215,208/251, 252/414, 252/439 preferred embodiment, a portion of thepreviously produced [51] Int. B01] 11/74, product effluent. Preferredcatalysts are the unsupported sul- ClOg 13/06, ClOg 23/16 fides of themetals from Groups V-B, Vl-B and VIII. Prior to [50] Field of Search208/ 108, an initial separation, hydrogen sulfide is commingled with the215; 252/414, 439 product effluent in order to convert the metalscontained v therein to the sulfides thereof. [56] References CitedUNITED STATES PATENTS 1,890,434 l2/l932 Krauch et al. 208/10 1 v 3 3 H s,3 B Make-up Hydrogen 4 2 f ,4 3 /4 L E 4 y l I /2 i /5 Amman/a I 8 t 5r a l l b S g /9 b 7 Q a e s u E '8 E g; 7 5 E /7 I 3 I a e s s a 9 l 5a u E 22 t g Q 2 5 1 l6 V 2/ t /6 l 2 1 z 20 :25

CATALYTIC SLURRY PROCESS FOR BLACK OIL CONVERSION WITH HYDROGEN ANDAMMONIA The process described herein is applicable to the conversion ofpetroleum crude oil residuals having a high metals content andcomprising a hydrocarbon-insoluble asphaltene fraction. Morespecifically, our invention is directed toward a method for effecting acatalytic slurry process, in the presence of hydrogen, in order toconvert atmospheric tower bottoms, vacuum column bottoms, crude oilresiduals, topped and/or reduced crude oils, coal oil extracts, crudeoils extracted from tar sands, etc., all of which are commonly referredto in the art as "black oil.

Petroleum crude oils, and particularly the heavy residuals derivedtherefrom, contain sulfurous compounds in exceedingly large quantities,nitrogenous compounds, high molecular weight organometallic complexesprincipally comprising nickel and vanadium as the metallic component andhydrocarbon-insoluble asphaltenic material. The latter is generallyfound to be complexed with sulfur, and, to a certain extent, with themetallic contaminants. A black oil is generally characterized inpetroleum technology as a heavy hydrocarbonaceous material of which morethan about 10.0 percent (by volume) boils above a temperature of about1,050 F. (referred to as nondistillables) and which further has agravity generally less than 20.0 APl. Sulfur concentrations areexceedingly high, most often in the range of about 2.0 to about 6.0percent by weight. Conradson carbon residual factors exceed 1.0 percentby weight and the concentration of metals can range from as low as aboutppm. to as high as about 750 ppm. by weight.

The process encompassed by the present invention is particularlydirected toward the conversion of those black oils contaminated by largequantities of insoluble asphaltenes and having a high metals contenti.e.containing more than about 150 p.p.m. by weight. Specific examples ofthe charge stocks to which our invention is adaptable include a vacuumtower bottoms product having a gravity of 7.l API and containing 4.1percent by weight of sulfur and 23.7 percent by weight ofheptane-insoluble materials; a topped" Middle-East crude oil having agravity of 110 API and containing about 10.1 percent by weight ofasphaltenes and 5.2 percent by weight of sulfur; and, a vacuum residuumhaving a gravity of 8.8 API, containing 3.0 percent by weight of sulfurand 4,300 p.p.m. by weight of nitrogen.

The utilization of our invention affords the conversion of such materialinto distillable hydrocarbons, heretofore having been consideredvirtually impossible to achieve on a continuous basis with an acceptablecatalyst life. The principal difficulty, encountered in a fixed-bedcatalytic system, resides in the lack of sufficient catalyst stabilityin the presence of relatively large quantities of metalsi.e. from about150 p.p.m. to as high as 750 p.p.m., computed as the elements-and,additionally from the presence of large quantities of asphaltenicmaterial and other nondistillables. The asphaltic material compriseshigh molecular weight coke precursors, insoluble in light hydrocarbonssuch as propane, pentane and/or heptane. The asphaltic material isgenerally found to be dispersed within the black oil, and, whensubjected to elevated temperature, has the tendency to flocculate andpolymerize whereby conversion to more valuable oil-soluble productsbecomes extremely difiicult.

Candor compels recognition of the fact that many slurrytype processeshave been proposed. Regardless of the various operating and processingtechniques, the principal difficulty resides in the separation of theeffluent to provide substantially catalyst-free distillable product,internal catalyst recirculation and spent" catalyst withdrawal. Successhas been achieved primarily through the use of intricate equipment atprohibitively high costs. An obvious alternative is to utilize the blackoil as the charge to a coking unit for the production of coke anddistillable hydrocarbons. In view of the steadily increasing demand for.distillable hydrocarbons, particularly motor fuels, jet fuels and stocksfor conversion into liquefied petroleum gas, coking is no longersuitable due to its relatively low yield of distillable hydrocarbons.Our invention affords a more economical and less difficult process fromthe standpoint of the desired product recovery, internal catalystrecirculation and catalyst withdrawal.

Therefore, in one embodiment, our invention provides a process forconverting an asphaltene-containing hydrocarbonaceous charge stock whichcomprises the steps of: (a) forming a reactive slurry of said chargestock, hydrogen, ammonia and finely divided catalyst containing at leastone metal component from the metals of Groups V-B, V-B and Vlll; (b)reacting said slurry in a reaction zone, or coil, at cracking conditionsincluding a pressure above about 500 p.s.i.g. and a temperature aboveabout 800 F.; (c) separating the resulting cracked product effluent, ina first separation zone, at substantially the same pressure and atemperature below about 900 F., to provide a first vaporous phase and afirst catalyst-containing liquid phase; (d) separating said firstvaporous phase in a second separation zone, at substantially the samepressure and a temperature in the range about 60 to about 140 F., toprovide a second liquid phase and a second vaporous phase, recycling atleast a portion of the latter to combine with said charge stock andhydrogen; (e) separating said first catalystcontaining liquid phase andsaid second liquid phase in a third separation zone, at a reducedpressure from atmospheric to about p.s.i.g., to provide a firstdistillable product'stream and a third catalyst-containing liquid phase;and, (f) separat' ing said third catalyst-containing liquid phase in afourth separation zone, at a temperature above about 700 F. and atsubatmospheric pressure to provide a second distillable product streamand an asphaltene/catalyst sludge.

Other embodiments of our invention are directed toward particularoperating techniques and preferred ranges of operating variables andconditions. Thus, the process is further characterized, in anotherembodiment, in that at least a portion of said first catalyst-containingliquid stream is recycled to combine with the charge stock. The catalystconcentration, within the slurry being introduced into the reactionchamber, is in the range of from about 1.0 to about 25.0 percent byweight, based upon fresh feed charge stock, and preferably from about2.0 percent to about 15.0 percent. ln a preferred embodiment, theprocess is further characterized in that said reactive slurry containsfrom 0.5 to about 10.0 percent by weight of ammonia. Since it ispreferred to conduct the conversion in the substantial absence ofhydrogen sulfide in the reaction zone, ammonia is injected, preferablyin the recycled gaseous phase, in sufficient quantity to neutralize thehydrogen sulfide liberated during the course of the reaction. Hydrogensulfide is then commingled with the reaction zone effluent in order toconvert the catalytic metals to the sulfides.

SUMMARY OF INVENTION The particular finely divided, solid catalystutilized in the present slurry process, is not considered to beessential. However, it must be recognized that the catalytically activemetallic component of the catalyst necessarily possesses both crac'kingand hydrogenation activity. In .most applications of our invention, thecatalytically active metallic component or components will be selectedfrom the metals of Groups V-B, VIB and VII] of The Periodic Table. Thus,in accordance, with The Periodic Table of The Elements, E. H. Sargentand Company, 1964, the preferred metallic components are vanadium,chromium, iron, cobalt, nickel, niobium, molybdenum, tantalum and/ortungsten. The noble metals of Group VIII, namely ruthenium, rhodium,palladium, osmium, iridium, and platinum, are not generally consideredfor use in a slurry-type process in view of the economic considerationsinvolved with these relatively expensive metals. The foregoing metalliccomponents may be combined with a refractory inorganic oxide carriermaterial, including alumina, silica, zirconia, magnesia, titaniamixtures of two or more, etc., the final composite being reduced to afinely divided state. in such a composite, the active metalliccomponents may exist in some refractory inorganic oxide carriermaterial. For this reason,

the preferred unsupported catalyst for use in the process of the presentinvention, comprises tantalum, niobium or vanadium with a vanadiumsulfide being particularly preferred. In theinterest of brevity, thefollowing discussion will be limited to the use of vanadium sulfides, inan amount of about 1.0 to

about 25.0 percent by weight, as the catalyst in the present slurryprocess.

Regardless, of the character of the catalyst, it may be prepared in anysuitable, convenient manner, the precise method not being essential tothe present invention. For exam ple, vanadium sulfides may be preparedby reducing vanadium pentoxide with sulfur dioxide, sulfuric acid andwater to yield a solid hydrate of vanadyl sulfate. The latter is treatedwith hydrogen sulfide at a temperature of about 300 C. to form vanadiumtetrasulfide. Reducing the vanadium tetrasulfide in hydrogen, at atemperature of above about 300 C., produces the vanadium sulfide whichis slurried into the system. As hereinbefore set forth, theconcentration of vanadium sulfide is preferably within the range ofabout 2.0 to about 15.0 percent by weight, calculated as the elementalmetal. Excessive concentrations do not appear to enhance the results,even with extremely contaminated charge stocks having exceedingly highasphaltene contents.

DESCRIPTION OF DRAWING In the accompanying drawing, illustrating oneembodiment of our invention, a simplified flow diagram is presented.Details such as pumps, instrumentation and controls, heatexchange andheat'recovery circuits, valving, startup lines and similar hardware havebeen omitted; these are considered to be nonessential to anunderstanding of the techniques involved. The utilization of suchmiscellaneous appurtenances, to modify the illustrated process flow, arewell within the purview of those skilled in the art. Similarly, it isunderstood that the charge stock, operating conditions, catalysts,design of fractionators, separators and the like are exemplary only, andmay be varied widely without departure from the spirit of our invention,the scope of which is defined by the appended claims.

with reference now to the drawing, the fresh feed charge stock, forexample a reduced crude oil, enters the process by way of line 1. Thecharge stock is commingled with a hydrogen-rich recycle stream from line3 and a vanadium sulfide catalyst-containing hot recycle stream fromline 2. The mixture continues through line 1 into reaction coil 6 at apressure above about 500 p.s.i.g. and a temperature above about 800 F.;preferred conditions are a pressure from 1,000 to about 3,000 p.s.i.g.and a temperature in the range of from 825 to about l,000 F. Thehydrogen concentration, within the reactive slurry entering reactioncoil 6, including makeup hydrogen introduced by way of line 4 is from1,000 to about 50,000 s.c.f./bbl., and preferably from about 3,000 toabout 20,000 s.c.f./bbl. In a preferred embodiment, the reactive slurryalso contains from 0.5 to about 10.0 percent by weight of ammoniaintroduced into the hydrogen-rich recycle stream through line 5.

The product effluent from reaction coil 6 is admixed with from 1.0 toabout 25.0 percent by weight of hydrogen sulfide from line 8, and themixture continues through line 7 into hot separator 9, at substantiallythe same pressure as it emanates from reaction coil 6. Prior to beingintroduced into hot separator 9, the hydrogen sulfide-containingreaction coil efiluent is utilized as a heat-exchange medium to lowerits temperature to a level in the range of from about 700 to about 900F. Hot

separator 9 serves the principal function of providing a principallyvaporous phase, line 10, and a catalyst-containing liquid phase, line16, the latter containing primarily those hydrocarbons boiling above atemperature of about 650 F. The vaporous phase in line 10 is cooled andcondensed to a temperature in the range of about 60 to about 140 F., andintroduced into receiver 11. The liquid phase in line 16 may berecycled, at least in part, by way of line 2 to combine with the freshfeed charge stock in line 1. Since hydrogen sulfide has been commingledwith the reaction zone effluent, prior to separation in hot separator 9,the catalyst being recycled by way of line 2, with the hot separatorliquid phase, is in the form of a sulfide. The quantity so recycled issuch that the combined liquid feed ratio to reaction coil 6 is withinthe range of about 1.1 to about 6.0. High-pressure receiver 11 provideshydrogen-rich vaporous phase, being withdrawn by way of line 12, whichvaporous phase is introduced into hydrogen sulfide removal system 13.The enriched hydrogen stream is recycled through line 3 by way ofcompressive means not illustrated in the drawing, and is admixed withmakeup hydrogen in line 4 and ammonia from line 5. Hydrogen sulfide iswithdrawn from the removal system by way of line 14, at least a portionof which is diverted through line 8 to combine with the reaction producteffluent in line 7.

That portion of the catalyst-containing liquid phase from hot separator9 not being recycled by way of line 2, continues through line 16 intoflash fractionator 17. Similarly, the liquid phase from high-pressurereceiver 11 is withdrawn by way of line 15 and introduced into flashfractionator 17, preferably at a locus above that through which the hotseparator liquid is introduced. The separation in flash fractionator 17is effected at a reduced pressure of from atmospheric to about p.s.i.g.and a reboiler, or bottom temperature in the range of 600 to about 800F. In the drawing, flash fractionator 17 is shown as separating theproduct into three individual streams. For the purposes of .thisillustration, a naphtha fraction, having an end boiling point of about400 F., and containing normally gaseous hydrocarbons, is withdrawnthrough line 18. A gas oil fraction, boiling up to a temperature ofabout 650 F., is withdrawn through line 19, while a heavier fraction,containing catalyst particles and unreacted asphaltenes is withdrawnthrough line 20. The latter is introduced into vacuum column 21 whereinseparation is effected to provide a light vacuum gas oil in line 22, aheavy vacuum gas oil in line 23 and, an asphaltene/catalyst sludge inline 24. In one embodiment, not illustrated in the drawing, vacuumcolumn 21 is operated in a manner which provides a slop-wax out which isrecycled to the reaction coil in admixture with a portion of theasphaltene/catalyst sludge. When this embodiment is practiced, a recyclestream from hot separator 9 is generally not effected. Theasphaltene/catalyst sludge may be subjected to a series of filtrationand washing techniques, utilizing a suitable solvent to remove residual,soluble hydrocarbons therefrom. The remainder of the sludge is generallyburned in air, resulting in vanadium pentoxide which is subsequentlyreduced with sulfur dioxide, sulfuric acid and water to produce vanadylsulfate. The procedure then follows the previously described scheme forthe preparation of fresh vanadium sulfide.

DESCRIPTION OF A PREFERRED EMBODIMENT This illustration of a preferredembodiment will be presented in connection with a commercially sealedunit designed to process 25,000 bbl./day of a Laguna reduced crudehaving a gravity of about 9.8 API. Other characteristics of the chargestock include an initial boiling point of 560 F., a 10.0 percentvolumetric distillation temperature of 700 F. and a 50.0 percentvolumetric distillation temperature of 1,000 F.; the crude containsabout 5,190 p.p.m. by weight of nitrogen, 9.6 percent by weight ofheptane-insoluble asphaltenes, 2.8 percent by weight of sulfur, about438 p.p.m. of vanadium and 74 p.p.m. of nickel, has a carbon/hydrogenatomic ratio of about 7.95 and an average molecular weight of about 598.

The reduced crude, in an amount of about 696 mols./hr., is admixed with208 mols/hr. of ammonia, 13,865 mols/hr. of a hydrogen-rich recycledgaseous phase (12,336 mols/hr. of hydrogen) and a hot liquid recycle inan amount to result in a combined liquid feed ratio of 2.0. The totalcharge, containing about 5.5 percent by weight of a vanadium sulfide, isintroduced into a reaction coil at a pressure of about 2,000 p.s.i.g.and a temperature of about 850 F. About 14 mols/hr. of hydrogen sulfideare added to the reaction coil effluent prior to the introductionthereof into a hot separator at a temperature of about 750 F. Theseparation effected in the hot separator is illustrated in table I, withreference being made to line numbers in the accompanying drawing. Forconvenience, the values are expressed in mols/hr. Not included are 208mols/hr. of neutralized hydrogen sulfide.

TABLE I: HOT SEPARATOR STREAM ANALYSES The vaporous phase from the hotseparator is cooled and condensed, and passed into a high-pressure(about 1,900 p.s.i.g.) receiver at a temperature of about 100 F. Ahydrogen-rich vaporous phase is recycled therefrom to the reaction coil.The normally liquid stream from the receiver is introduced into a flashfractionator functioning at a temperature of 750 F. and a pressure of 75p.s.i.g. The hot separator liquid stream is also introduced into theflash fractionator, but through a locus below that through which thereceiver stream is introduced. The separation effected in the coldreceiver is presented in the following table II:

In this illustration, the flash fractionator provides an overhead streamcontaining hexanes and lower-boiling components, a side-cut naphthastream of heptanes and other hydrocarbons boiling up to 400 F., a lightgas oil out and a bottoms, catalyst-containing stream comprising 650F.-plus hydrocarbons. The latter is introduced into a vacuum column (55mm. of Hg.) at a temperature of 800 F. A heavy vacuum gas oil isrecovered and an asphaltene/catalyst sludge is removed to a catalystrecovery system.

The overall yields and product distribution are presented in thefollowing table III:

TABLE III: PRODUCT DISTRIBUTION AND YIELDS the process encompassed byour invention is effected, and illustrates the benefits afforded throughthe utilization thereof.

We claim as our invention:

1. A process for converting an asphaltene-containing hydrocarbonaceouscharge stock which comprises the steps of:

a. forming a reactive slurry of said charge stock, hydrogen, ammonia anda finely divided catalyst containing at least one metal component fromthe metals of Groups V-B, VI-B and VIII;

. reacting said slurry in a reaction zone, or coil, at crackingconditions including a pressure above about 500 p.s.i.g. and atemperature above about 800 F.;

c. separating the resulting cracked product effluent, in a firstseparation zone, at substantially the same pressure and a temperaturebelow about 900 F., to provide a first vaporous phase and a firstcatalyst-containing liquid phase;

d. separating said first vaporous phase in a second separation zone, atsubstantially the same pressure and a temperature in the range of about60 to about 140 F., to provide a second liquid phase and a secondvaporous phase, recycling at least a portion of the latter to combinewith said charge stock and hydrogen;

e. separating at least a portion of said first catalyst-containingliquid phase and said second liquid phase in a third separation zone, ata reduced pressure of from atmospheric to about p.s.i.g., to provide afirst distillable product stream and a third catalyst-containing liquidphase; and,

f. separating said third catalyst-containing liquid phase in a fourthseparation zone, at a temperature above about 700 F. and atsubatmospheric pressure, to provide a second distillable product streamand an asphaltene/catalyst sludge.

2. The process of claim 1 further characterized in that said catalyst isan unsupported sulfide of at least one of the metals from Groups V-B,VI-B and VIII.

3. The process of claim 1 further characterized in that said catalystconstitutes from 1.0 to about 25.0 percent by weight of said chargestock, as the elemental metal.

4. The process of claim 2 further characterized in that said catalyst isan unsupported vanadium sulfide.

5. The process of claim 1 further characterized in that hydrogen sulfideis commingled with said cracked product effluent in an amount of from1.0 to about 25.0 percent by weight, as elemental sulfur.

6. The process of claim 1 further characterized in that said reactiveslurry contains from 0.5 to about 10.0 percent by weight of ammonia.

7. The process of claim 1 further characterized in that said slurry isreacted at a pressure from 1,000 to about 3,000 p.s.i.g. and atemperature in the range of from 825 to about 1 ,000 .F.

2. The process of claim 1 further characterized in that said catalyst isan unsupported sulfide of at least one of the metals from Groups V-B,VI-B and VIII.
 3. The process of claim 1 further characterized in thatsaid catalyst constitutes from 1.0 to about 25.0 percent by weight ofsaid charge stock, as the elemental metal.
 4. The process of claim 2further characterized in that said catalyst is an unsupported vanadiumsulfide.
 5. The process of claim 1 further characterized in thathydrogen sulfide is commingled with said cracked product effluent in anamount of from 1.0 to about 25.0 percent by weight, as elemental sulfur.6. The process of claim 1 further characterized in that said reactiveslurry contains from 0.5 to about 10.0 percent by weight of ammonia. 7.The process of claim 1 further characterized in that said slurry isreacted at a pressure from 1,000 to about 3,000 p.s.i.g. and atemperature in the range of from 825* to about 1, 000* F.